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BG, The charring on the bottom bar of the frames occurs when the JB200 is not pushed far enough into the hive to overcome the weight of the handle and wiring, causing the heater and pan to be lifted up and come into contact with the frames. This can also cause the heater and pan to become tilted sideways and the liquified acid will spill out reducing the effectiveness of the treatment.

Sometimes ladder comb and other debris will prevent full insertion of the unit, so to overcome this problem keep a scraper handy to slide into the hive opening and clear a path for the vaporizer.

Thanks for your insight! Good idea on the scraper for clearing the way below the frames!

My two hive pallets I made have 3/4" spacers, so it should provide enough clearance for the tool to slide in as I believe it's only 3/8" inch tall. I'll remember to slide the vaporizer to the half way point when using it for sure!

Another question about the oxalic acid vapors!! How far will they travel in the air before becoming a non-issue to other people? Lets say I do a couple hives in town in a housing development or back yard.

BG, I have only my personal experience to give you, and that is if you seal the hive entrance with a cloth before energizing the vaporizer you should have very little if any leakage, and if a little leakage does occur it seems to dissipate rather quickly. When the hive has been sealed for the required 10 minuets the OA vapor particles will be circulated in the hive by the bees fanning it and will settle in the hive where they will do the most good.

There are people who use the vaporizers without sealing the hive entrance but a good amount of the OA vapor particles will be lost out the front of the hive creating a cloud of vapor which can be hazardous and also make the treatment less effective on Varroa. The JB200 Heilyser holds a maximum of 2 grams of OA which is the minimum amount required to treat a double deep hive , so to loose the vapor out the entrance is to loose effectiveness of treatment.

Not sealing the entrance is a faster way to treat the hives and this is why this method is used but the hive is not getting the full effect of the OA. To get a full effect of treatment on a non sealed entrance one could use two vaporizers per hive treatment, applying a total of 4 grams of OA per a double deep hive to make up for the loss of vapor out of the open entrance but one would then have the vapor cloud to contend with.

In a nutshell, seal the entrance during treatment and you should be good to go, I do not wear a mask and have no problems, but I do wear safety glasses when handling the OA crystals.

I can't find it now. But at one time I read a study on OA vaporizing and at what dosage it has worked basically. Although 2 grams is what is standard for a double deep hive. It is about 3 times what is necessary to treat the mites. I amount suggesting anyone reduce their dosage as it has been suggested due to things like leaking. how well the vapor migrates through the hive etc.

Anyway the overall impression is that the recommended dosage already has the fudge factor included in it and has basically been proven reliable. I just stick with the 1 gram per deep ratio and have found that it still works even when it has not necessarily worked well. I don't get bellowing clouds of vapor with my method. But as far as I can tell it still gives the mites a wallop. My method vaporizes the OA over about a three minute period rather than quickly like the hot plates do. I am looking for a better tool to heat the acid with..

Mark I did a before in this case. I did not do an after as I was already running into cold weather and barely got the treatment in. No screen bottom board so I would have had to open the hive to inspect. I will say my count before showed my hive was way over the top. I did it by pulling drone brood. I found as many as two mites per pupa or something like 9 mites per 20 pupa. I have information that says 1 mite in 8 pupa requires treatment. So what was I about 4 times the limit.

I actually saw a change in the behavior of my bees after three treatments (three weeks) they still appear strong to this day. Yes I am holding my breath. Everything I see is encouraging but I have no good numbers on mite count after treatment. Just other signs that say it did work at least to a significant degree.

Another question about the oxalic acid vapors!! How far will they travel in the air before becoming a non-issue to other people? Lets say I do a couple hives in town in a housing development or back yard.

Dave Cushman in England says: “Some are concerned about Oxalic acid vaporisation producing a great deal of toxic vapour, but the point of the treatment is that the oxalic acid re-condenses within the hive very rapidly and coats everything in sight. Leakage will occur, but it will be a minor amount and the fine crystals will fall out of suspension fairly rapidly. If due notice is taken of sealing up the hive and prevailing wind direction, there should be very little exposure to the operative.

This is from an article I found , it tells just about everything you would want to know about OA.